'Is it heroic to follow your heart, to fall so deeply in love that you don’t have a choice?’ she asks over dinner at a bustling Moroccan restaurant in New York.

We’re on the Lower East Side of Manhattan, close to the home she shares with Daniel Craig and her five-year-old son, Henry (from her relationship with the director Darren Aronofsky).

No, the 41-year-old actress is not talking about her marriage of five months to the Bond star, but the desperate, unrequited love that is the subject of her latest film, The Deep Blue Sea, a beautiful adaptation of Terence Rattigan’s 1952 play.

Weisz has been cast as Hester Collyer, the wife of a judge (played by Simon Russell Beale) who races headlong into an affair with a charismatic, dashing ex RAF pilot, Freddie Page (Tom Hiddleston).

Tossing aside wealth, respectability and security with reckless abandon, her character moves into a grim Ladbroke Grove bed-sit with Page, who drinks heavily, constantly reminisces about his wartime glory days and dallies with her affections without any interest in commitment.

'I liked the idea of playing someone who wasn’t embarrassed to completely humiliate herself,’ says the actress. 'Tom [Hiddleston] describes it as the triumph of passion over the intellect.’

The drama is an evocative depiction of post-war London in the early 1950s, suffused with cigarette smoke and jolly pub sing-alongs.

Weisz delivers a heartbreaking but unsentimental performance as Hester, which has echoes of Celia Johnson’s portrayal of Laura Jesson in David Lean’s 1945 classic, Brief Encounter, and has already been mentioned as a possible Oscar contender.

Hester Collyer strikes me as a victim, I say. Weisz disagrees. 'She doesn’t do what’s expected of her and I think that’s pretty valiant and heroic. It’s fabulous.

'You could say she is the stereotype of a woman who’s laying herself down at a man’s feet and waiting to be trodden all over. But she isn’t just that.

'This story is about someone who has surrendered to her love. That’s what romance with a capital R means, doesn’t it?’

Are women, I wonder, culturally conditioned to be more susceptible to romantic obsession? 'It’s a good question,’ says Weisz. 'I think traditionally in stories women behave more like Hester.

'I wonder if we’re predisposed to think that’s how we’re supposed to behave. I don’t know, but I do think it is still a very contemporary story about anyone who chooses the heart over the head.’

Weisz herself may have chosen the heart over the head.

Twelve months ago she split up with Darren Aronofsky, her partner of nine years; soon after that it was revealed that she was seeing Daniel Craig, who had split up with his long-term fiancé, Satsuki Mitchell.

Weisz and Craig were married in June this year. But she won’t discuss their relationship with me.

Prior to Aronofsky (who directed Black Swan) the actress had relationships with Neil Morrissey and Sam Mendes and has been quite open about her personal life in the past.

Her current reticence, I suspect, is influenced by the notoriously private Craig.

'I’m sorry,’ she says with a smile, 'I’m a newly wed, I’m still a blushing bride and it’s really private. I can’t tell you anything. Come back to me later.’

It is obvious, however, that Rachel Weisz is a woman in love. As she walks towards me striding past cafés, book shops and an 'Asian Bodywork’ health centre, the spring in her step is plain to see.

She looks radiant, casually dressed in black Earnest Sewn jeans, boots and a black Margiela T-shirt, with her long hair flowing and a dazzling smile lighting up her face.

We find a table in the back of the restaurant with its tiled tables, brick walls, Moroccan lamps and jars full of lentils.

She orders chicken tajine, couscous and salad, refusing wine because she’s shooting a scene for her next movie, The Bourne Legacy, at 3am tomorrow.

She rolls her eyes, adding. 'I do drink wine. I read that I wasn’t drinking alcohol because I was pregnant. It’s not true.’

Would she like another baby?

'Absolutely no comment. Oh my Lord, I was asked that recently by a journalist and I think I said, “You never know,” and it was turned into something else entirely. I’m not complaining. I am just realising that anything I say…’

She runs her fingers through her hair and sighs.

Craig and Weisz reportedly became close while filming Jim Sheridan’s new thriller, Dream House, which opens next week. They play a married couple who move to the country and discover that their new home is haunted.

Unsurprisingly, there is great chemistry between the pair. 'I really enjoyed working with him,’ says Weisz.

'We have actually known each other a long time, since our early twenties,’ she adds, explaining that they performed together back then in Les Grandes Horizontales, produced by the experimental theatre group Talking Tongues, which she co-founded at Cambridge University.

'He is a very good actor,’ she says. At which point she puts down a forkful of couscous, looks me squarely in the eye and we both dissolve into laughter.

Weisz has a loud infectious laugh and a sense of humour, but she is not the easiest person to interview.

When I ask a question, it is often parried with another question: do you think what women want from a relationship changes as they get older?

'What do you think?’

Readers are interested in your views not mine – I’m writing a profile piece about you.

'What’s expected in a profile?’

She can also be a bit evasive, worried about words being taken out of context. I ask whether, in her view, children benefit from mothers who have fulfilling careers.

'I don’t want to make a sweeping statement,’ she sighs. 'I once said that in the last trimester of my pregnancy I had a glass of red wine; it turned into me supposedly saying pregnant women should drink.’

There are no platitudes, though, even when the conversation turns to the thorny subject of plastic surgery and the challenges of ageing in her youth-obsessed industry.

In the past she has said, 'Botox should be banned for actors, as steroids are for sportsmen. Acting is all about expression; why would you want to iron out a frown?’

Today she says: 'I think there are two aspects to ageing: there’s the physical side and what’s happening inside. [The latter] gets much better for me; I feel a lot happier, more confident now.

'But am I enjoying physically ageing? I don’t know anyone who would actually enjoy that. People say lines are a map of a person’s experiences. I can’t see the upside of it.

'I’m not thinking of having a face lift yet - ask me again in a decade.’

The actress hasn’t lost her Home Counties accent despite a decade living in America. Weisz’s parents fled to England to escape Nazi persecution just before the outbreak of the Second World War.

'They were both small children when they had to leave their homes. They were lucky to escape.’

Her Hungarian father, George, became a medical inventor and industrialist and her Austrian mother, Edith, taught English as a foreign language and later trained as a psychotherapist.

Weisz, who also has an older sister, Minnie, an artist, describes Hampstead Garden Suburb in London, where they grew up, as 'very suburban, crazy expensive and incredibly privileged.

'But there’s not anything to do. There are no shops or pubs – just houses.’

Her parents split up when Weisz was 16.

How did the divorce affect her? 'Obviously they didn’t get along, but I had a lot of love from both my parents. I think kids can survive anything if they’re really loved.’

But she does admit that her teenage years were difficult. Weisz attended three private girls’ schools (North London Collegiate, Benenden and St Paul’s).

'I was asked to leave North London Collegiate, but my mum doesn’t like me to say I was expelled,’ she says with a laugh.

'I didn’t try to burn down the school or anything like that; it was just anti-authority issues. I didn’t think the teachers had the right to tell me what to do. I would just disobey, talk in the classroom, get very bad grades.

'I was not a good person to have in the classroom, to put it mildly.’

It was a charismatic English teacher at St Paul’s, Miss Gough, who persuaded Weisz to knuckle down.

'I was very nearly asked to leave that school, too, for ongoing disobedience – the French teacher refused to teach me – but Miss Gough, who later became headmistress, completely inspired me.

'She saw through me and she scared me and I guess none of the other teachers did that. We read a lot of poetry. I started to read everything and ended up studying English at Cambridge.’

It was at Trinity Hall that Weisz became immersed in theatre, forming Talking Tongues.

After university, there were stage roles – including playing Gilda in Noël Coward’s Design for Living – and parts in television dramas and films, such as Bernardo Bertolucci’s Stealing Beauty (1996) and Michael Winterbottom’s I Want You (1998).

But it was The Mummy (1999), a special-effects crowd-pleaser, that catapulted her to stardom in America in her late twenties.

She went on to star in About a Boy (2002) with Hugh Grant, based on Nick Hornby’s bestselling novel, and The Constant Gardener (2006), for which she won a best supporting actress Oscar.

I remark that, along with the accolades, she has frequently been described as the most beautiful woman in film. She pulls a face and points to a willowy blonde at the next table.

'That’s beautiful. She looks like a supermodel. I have a stylist, a make-up artist and a hairdresser who make me look like you see me on the red carpet.’

Weisz won an Olivier award last year for her portrayal of Blanche Dubois in the West End production of Tennessee Williams’ A Streetcar Named Desire.

She is currently filming Sam Raimi’s Oz: The Great and Powerful, a prequel to The Wizard of Oz, co-starring Michelle Williams and James Franco.

But it is tales of pioneering women that interest her most, like her forthcoming role in The Whistleblower, a harrowing true story in which she plays Kathryn Bolkovac, an American ex-policewoman who worked as a peacekeeper in Bosnia and exposed a sex-trafficking scandal.

'Kathy’s story is completely extraordinary. I think people who stick their necks out and risk their lives to do what they believe is right are inspiring.

'I’m very successful and do lots of films but I’ve never actually done anything extraordinary.’

Hollywood doesn’t see it that way. The director Tony Gilroy (whose films include Michael Clayton and State of Play) cast her in The Bourne Legacy which is likely to be the splashiest blockbuster of 2012.

'There’s a lot of stunt work, shooting and bad guys. I’ve had to start doing a bit more exercise. I’ve been running at the gym on an incline – it’s painful.’

Any tips from her impressively ripped husband? 'We’ve been to the gym together but we do very different training,’ she says, laughing.

Beyond that, she can’t reveal anything about the film. 'Believe it or not, I can talk about Bourne as much as I can talk about my marriage!’

And with that Rachel Weisz gets up to leave, heading home to the spy who loves her, her secrets safe.